The invention relates generally to a device and method for relief of symptoms of repetitive strain injuries and more specifically to plastic deformation of connective tissues in the hand and forearm.
There are many contemporaneous references describing a common type of repetitive strain injury (RSI) referred to as carpal tunnel syndrome. This syndrome results from an abnormal condition of the `carpus,` the human wrist. The carpus consists of eight bones arranged into two rows. The bones closest to the hand form a channel referred to as the carpal tunnel. This channel provides the conduit for the median nerve and the tendons and arteries connected to the thumb and fingers.
The detailed anatomy of the tendons passing through the carpus is well-documented and beyond the scope of this application. FIG. 1 and FIG. 2 illustrate, in a simplistic way, the main muscle/tendon structures implicated in the preferred embodiment. FIG. 1 is a view of the superficial muscle layer of the front of the left forearm. There are five muscles: the pronator radii teres, the flexor carpi radialis, the flexor carpi ulnaris, the flexor sublimis digitorum, and the palmaris longus. FIG. 2 is a view of the deep muscle layer of the front of the left forearm. There are three muscles: the flexor profundus digitorum, the flexor longus pollicis, and the pronator quadratus.
These muscles of the superficial layer extend from the internal condyle (near the elbow) past the carpus to the hand. For the deep layer, the muscles begin at the upper three-fourths of the anterior and inner surfaces of the ulna and extend past the carpus to the tips of the fingers. These muscles include tendon structures that connect to the bones of the hands. Many of these tendons pass through the carpal tunnel, and some pass under an annular ligament that surrounds a portion of the carpus.
When the carpal tunnel becomes restricted, such as inflammation of soft tissues of the wrist and the carpal tunnel, pressure is applied to the median nerve. Such pressure results in pain, tingling and numbness in the hand and fingers. The soft tissues may become inflamed from injury, arthritis, repetitive motion or from no particularly obvious cause.
X-ray examination of the carpus of persons suffering from certain types of carpal tunnel syndrome have shown compaction of the spaces surrounding the wrist bones, particularly the longitudinal spacing. One conventional treatment to relieve carpal tunnel syndrome is to cut the annular ligament. Once cut, spacing surrounding the wrist bones temporarily increases, particularly laterally. However, once separated laterally, the wrist bones may be more susceptible to further longitudinal compacting, possibly further aggravating the condition.
Other treatments for carpal tunnel syndrome include exercises designed to improve the strength of the forearm muscles. Unfortunately, the exercises recreate the environment that is implicated in creating the laterally compacted wrist bone condition. Exercises, like repetitive actions, are a form of resistance training that results in the strengthening of the forearm muscles responsible for clenching the fingers and thumb. Muscles, in response to resistance training, become stronger by increasing the number and density of muscle fibers. Unfortunately, the strength increase is typically asymmetric, with the clenching muscles becoming stronger than the corresponding `unclenching` muscles due to the nature of the repetitive stress. (In other cases, the flexors and extensors (the clenching and unclenching muscles) may both become strengthened and result in compaction of the effected joint.) The asymmetric strengthening of the clenching muscles causes increased stress on the carpal tunnel and longitudinally compacts the wrist bones.
The prior art includes various types and configurations of exercise gloves specifically designed to enhance and build one or more muscles of the hand and/or forearm. Such devices are active devices and use of these devices in the preferred way is believed to exacerbate the conditions addressed by the present invention.